3/4 Mercury Redstone

Discussion in 'Scratch Built' started by Feckless Counsel, Nov 28, 2015.

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  1. Nov 28, 2015 #1

    Feckless Counsel

    Feckless Counsel

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    TRF,

    I am always impressed by the modeling work of Steve Eves, Vern Hoag and Karl Hemphill. If memory serves it’s been about 7 years since anything of that scale has flow in the US. Perhaps it’s time we get back to it?

    I would propose a 3/4-scale Mercury Redstone for flight March / April of 2017. Specifications of the rocket are roughly:

    52.5-inch diameter.
    750-inch height including escape tower.
    500-pound pad weight.
    Single experimental 8-inch x 6-grain Q-impulse motor.
    Target altitude 5,500 feet.

    I believe the rocket can be built on budget of $4,000. Propulsion will cost another $4,000. By luck and with the blessings of a great wife I have sequestered $5,000 towards the project.

    I also have a preliminary offer to warehouse space for the construction and short term storage of the project. There is also a preliminary plan for transportation to and from the launch site.

    Feckless Counsel
     
  2. Nov 28, 2015 #2

    Feckless Counsel

    Feckless Counsel

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    TRF,

    The rocket would be built using semi-monocoque construction. The basic airframe consists of 9 interlocking sections. Each section is made from four 6mm plywood formers intersected by twenty 3.5mm plywood stringers. Former and stringer are notched “half lap” and are 3-inches wide / 3-inches web. Five pieces of 1-inch fiberglass tubing act as longerons. The fiber glass tube also receive 3/4-inch solid fiberglass dowel pin to secure sections together.

    Sections, once assembled and glued, are wrapped in a single turn of 6-ounce fiberglass cloth saturated in epoxy dyed white. Note white is the primary color of the Mercury Redstone. I do plan to lay fiberglass flat, let it gel a little, and then roll the airframe over.

    Feckless Counsel

    Section view.jpg
     
  3. Nov 29, 2015 #3

    mpitfield

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    Great project! I love these big projects, Steve Eves Saturn V launch was what inspired me to get back into this hobby.

    A few questions.

    Where do you plan on launching it?
    Are you looking for help if so what tasks?
    Are you looking for sponsors or another financial partner/s?
    Commercial or EX?
     
  4. Nov 29, 2015 #4

    Feckless Counsel

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    TRF,

    One critical question is can such a gossamer construction survive assembly and flight. I believe the answers is yes.

    Stress analysis has been performed on the proposed airframe. Note this is a preliminary analysis on the 530-inch (44-foot) airframe tube alone. Three situations are considered:

    1. Simply supported on each end under its own weight.
    2. Accelerated in a vacuum at 10G vertical (scenario 1)
    3. Accelerated in a vacuum at 10G but 6-degrees off vertical (scenario 2)

    As illustrated in the first picture total deflection on the basic airframe is just 4mm under its own weight. That is less than 0.03% indicating a quite “stiff” structure. Skin stresses are in megapascals and well below the 262-megapascal yield stress of fiberglass.

    The second picture address acceleration. At 10G skin and plywood frame a well below yield. Plywood is anisotropic meaning its strength is not the same in all directions. Given the worst possible yield strength of Baltic birch is 29-megapascal this airframe is 50% yield at 10G acceleration in a vacuum.

    Given these results I plan to build two sections as proof of concept. Those sections will include the deployment scheme so that can also be tested. More on the deployment scheme later.

    Feckless Counsel

    Simply supported bending.jpg

    Frame stress study.jpg
     
  5. Nov 29, 2015 #5

    Feckless Counsel

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    mpitfield,

    Thanks for your reply and appreciate we share the same inspirations.

    Assuming I actually get it done this will be an MDRA exclusive.
    Labor is always appreciated especially recovery.
    I think the program is financed but might ask for loans of big parachutes.
    Experimental motor.

    Feckless Counsel
     
  6. Nov 29, 2015 #6

    kcobbva

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    Amen! Will watch this thread with gleeful delight. I have shown Steve's video on youtube to so many people. It was the most amazing thing. I believe this will be right up there, with an amazing rocket!!
     
  7. Nov 29, 2015 #7

    noffie79

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    Subscribed! Can't wait to see this
     
  8. Nov 29, 2015 #8

    dixontj93060

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    What do you use for your white dye?
     
  9. Nov 29, 2015 #9

    Feckless Counsel

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    dixonj93060,

    Data suggest aniline dye has good color saturation with minimal affect to adhesion.

    Feckless Counsel
     
  10. Nov 29, 2015 #10

    mpitfield

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    I looked at the MDRA website and based on Centreville to Toronto that would be about a half day drive for me...I would love to attend this one and if so lending a helping hand where I could would be a treat. I need to work on a cover story to convince the wife and kids on why we need to go in that direction, oh and there just happens to be a big rocket launch!
     
  11. Nov 29, 2015 #11

    dixontj93060

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    I have used Titanium Dioxide in the past. First try was a paste in a base of mineral oil. Tint worked great and didn't notice any real effect on the epoxy cure. But I'm not a chemical engineer, there may be a better base to use.
     
  12. Nov 29, 2015 #12

    Cl(VII)

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    Might have to make a trip to the in-laws for this one. Not a bad drive from Frederick.
     
  13. Nov 29, 2015 #13

    3stoogesrocketry

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    Wow this makes my full scale Iris look like a Estees RTF model. I am really looking forward to this project.

    Eric
     
  14. Jul 17, 2016 #14

    Feckless Counsel

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    TRF,

    Some updates to this project for those interested. Attached is a CAD "skin" demonstrating general shape of the 3/4 scale model. Note the structural references in the booster section.

    Feckless

    Redstone Skin.png
     
  15. Jul 17, 2016 #15

    Feckless Counsel

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    TRF,

    General detail of the booster is shown in the first attachment. A fin is illustrated along with CAD detail of the thrust plate and one fin former.

    Feckless

    Redstone Booster.png

    Redstone Fin Assembly.png

    Redstone Fin Former A.png

    Redstone Fin Former B.png
     
  16. Jul 17, 2016 #16

    mpitfield

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    I am excited to see an update on this one, do you think 2017 is still a realistic target, if not, 2018?
     
  17. Jul 17, 2016 #17

    dhbarr

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    Wow.

     
    Last edited: Jul 17, 2016
  18. Jul 17, 2016 #18

    cjp

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    In 2010 Steve had his Saturn 1B at the Cleveland Airshow.I was a volunteer that helped out at the display tent that we had our rockets in.Steve's Saturn 1B was displayed on the trailer that served as the launch pad and tower.I think it was 21ft. tall.A thing of beauty.After the show we took the rocket apart as it was a 2 stage for the trip back to his shop.I did not make it to Price Md. to watch the launch but had the pleasure of helping Steve launch a few of his smaller rockets at a club launch a few years ago.It was my first time seeing a K motor.Steve launched 2 rockets on K's.Really a great guy.Hope you have a successful build and launch with your Redstone.
     
  19. Jul 18, 2016 #19

    GregGleason

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    Merc Redstone fan, so I have to subscribe.

    Greg
     
  20. Jul 18, 2016 #20

    Feckless Counsel

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    TRF,

    Please see attached detail of the escape tower. Plan is to fabricate the tower from stock tubing with 3D printed joints.

    Feckless

    escape tower.png

    escape tower detail.png
     
  21. Jul 18, 2016 #21

    GregGleason

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    Are the printed joints plastic? If so, I would be concerned that they might break apart under the aero loads.

    Greg
     
  22. Jul 22, 2016 #22

    Feckless Counsel

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    TRF,

    Please see attached surface detail of the Mercury capsule.

    Mr. Gleason,

    Your point on printed parts is well noted. Those cannot be PLA. I think we've all learned PLA turns to snot in the sun. Team does have access to laser sintered nylon. I'm reasonably confident in that material. It is as durable as injection molded parts.

    Mpitfield,

    I am still hopeful this project will fly in 2017. Given MDRA is hosting LDRS next spring this launch may have to wait for Higgs Farm the fall of 2017. That presumes, of course, we finish the build and that this project is acceptable to MDRA. I think their BOD need some time to review construction details and field logistics.

    Feckless

    Redstone capsule.jpg
     
  23. Jul 24, 2016 #23

    AdAstraPerAspera

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    I would start talking to MDRA sooner rather than later.

    Steve is a great guy, but don't forget that he had a lot of help. He was working with and bouncing ideas off all the smartest, most experienced people at MDRA right from the start. That is why they let him fly.
     
  24. Jul 24, 2016 #24

    AdAstraPerAspera

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    BTW, you can always look into laser simmered metal parts. They can make printed parts in just about any material now...
     
  25. Jul 24, 2016 #25

    Feckless Counsel

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    TRF,

    This project requires about 850 square-foot of surface covering making that material one of most economically sensitive choices. Economy is complicated by a set of performance requirements ripe for debate. I say debate because such requirements are not easily calculated. Too much math spoils the hobby. The tendency, after some debate, is overdesign. Nevertheless I present two options for your debate:

    1. G10 sheet 0.010 inch thick. Tensile strength 30KSI. Density 0.065 pounds per cubic-inch. Elongation at break 0.3%. Cost $3 per square-foot.
    2. Electrical grade Kraft paper 0.020 inch thick. Tensile strength 10KSI. Density 0.025 pounds per cubic-inch. Elongation at break 9%. Cost $1 per square foot.

    Other suggestions are welcome considering objectives:

    1. About $2.00 per square-foot
    2. Available in minimum sheet size 60 x 85 inch
    3. Rigid enough to hold a cylinder across frame’s stringers
    4. Flexible enough to follow fin contours. Say a 3-inch bend radius.
    5. Fire resistant
    6. Bonds with epoxy and paint

    Feckless
     
  26. Jul 25, 2016 #26

    Bluegillbronco2

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    Right now I am building the New Estes Mercury Redstone. I am really interested to see were this build goes!
     
  27. Jul 30, 2016 #27

    Feckless Counsel

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    TRF,

    Our team has fabricated an 80 degree arc-length of airframe to improve our understanding of this design. Principle goals are:

    1. Verification of slot dimensions for tight and flush fit
    2. Confirmation of CNC house tolerances
    3. Drape of skin material
    4. Rigidity of assembly

    First attachment illustrates our sample pieces. Note a yardstick is included for scale:

    A. Former, 6mm thickness, 3-inch web, Baltic birch plywood
    B. Stringer, 3mm thickness, 3-inch web, Baltic birch plywood
    C. Longeron, 1-inch OD, ¾-inch ID, pultruded fiberglass

    Second attachment illustrates the assembled frame. Fit of plywood pieces is perfect. Stringers sit flush to formers with a firm hand squeeze. The assembly pulls itself to square. Longeron fit is just a little tight and needs adjustment to facilitate bonding.

    Third and fourth attachments illustrate skin application. The 0.010-inch thickness G10 sheet drapes nicely to our contours. It is light, tough and tensile strong. It is certainly the superior material. We are still seeking a domestic source to provide that in 60 x 84 inch format. Otherwise we will have to consider Asian imports.

    Everything shown is dry fit. Time to apply adhesives and do some abuse testing.

    Feckless Counsel

    Redstone parts labeled.jpg

    Redstone assembled section.jpg

    Redstone section skinned top.jpg

    Redstone skinned end.jpg
     
  28. Jul 31, 2016 #28

    Coop

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    Feckless, I've always enjoyed your build threads and watching your launches--fascinating from concept to landing.

    For separation and recovery, are you going to do rotating cams or what? I don't imagine slip joints would be ideal with the stringers, right?

    But as always... Fascinating work. Eagerly awaiting further updates!


    Later!

    --Coop
     
  29. Aug 1, 2016 #29

    burkefj

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    I'm glad to see a large lightweight rocket project, where it actually has a built up structure instead of just tubes and 2x4's...Interested to see your plan for thrust and recovery attachment/loading to the airframe.

    Frank
     
  30. Aug 3, 2016 #30

    MaxQ

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    That does look pretty darn cool.....
     

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